Comment on Activity 1

The Exploration Activity does not have a unique answer. For example, you might have estimated the hourly temperatures from Figure 1 and come up with the numbers in Table E1.

Table E1   Hourly temperatures at BWI airport, 12/18/06
Hour Temp   Hour Temp
0:00
49
12:00
71
1:00
48
13:00
70
2:00
49
14:00
69
3:00
48
15:00
67
4:00
50
16:00
64
5:00
49
17:00
61
6:00
48
18:00
58
7:00
49
19:00
58
8:00
53
20:00
55
9:00
59
21:00
53
10:00
63
22:00
52
11:00
67
23:00
51

The average of these temperature values is `54°`. Note that

  1. Neither the reported high (`72°`) nor the reported low (`47°`) appears in this table as an "on-the-hour" measurement.
  2. The average of the hourly measurments is quite different from the reported average (`60°`).
  3. It does not make sense to report the average from Table E1 with more than 2 SD, since these data are, at best, 2 SD.

With access to estimates of more temperature values (e.g., from a continuous drum recording), you can easily imagine how to modify this procedure to improve your calculation of the average: Use half-hour intervals, quarter-hours, perhaps even readings every minute or every second. This means many more numbers to average, but the procedure is the same: Add them up, and divide by the number of them. If the data are being recorded by computer, that should be easy, even at one-second intervals.